Comparison of speech perception between monaural and binaural hearing in cochlear implant patients

OBJECTIVE: To assess the advantages of binaural hearing for cochlear implant (CI) users using a hearing aid (HA) for the contralateral ear. MATERIAL AND METHODS: The subjects comprised 3 males and 3 females (age range 48-84 years). All of them had been using a CI and HA for > 6 months. Their speech perception was examined in quiet using monosyllables and Japanese Hearing in Noise Test (J-HINT) sentences. Speech perception in noise was examined using J-HINT sentences. Late cortical waves were measured while subjects listened to 1 kHz frequent and 2 kHz target tone stimuli. The latency of the event-related potential (P300) wave was compared for monaural and binaural hearing conditions. RESULTS: Three subjects showed significantly better results for binaural than monaural (CI alone) hearing for monosyllables and HINT sentences (p < 0.05; paired t-test). Subjects with better speech perception had been using an HA for longer than those with poor performance (18.3 vs 4.0 years). The overall average score was better for binaural than monaural hearing in the speech perception test under quiet and noisy conditions. Comparison of the latency of the P300 wave under monaural and binaural hearing conditions showed a significantly shorter latency for the latter (p = 0.02; paired t-test). CONCLUSIONS: Although the use of an HA alone showed marginal benefit for CI users, binaural hearing (CI+HA) resulted in a significant improvement in speech perception under various circumstances.     

Assessing binaural/bimodal advantages using auditory event-related potentials in subjects with cochlear implants

Objective

To assess the advantage of binaural and bimodal hearing for subjects with cochlear implant (CI) using auditory event-related potentials as well as speech perception tests.

Subjects and methods

The subjects comprised four binaural CI users (CI/CI group) and eleven bimodal CI users, who wore a hearing aid (HA) contralaterally (CI/HA group). All subjects had used binaural or bimodal fitting for over 6 months. Their speech perception was examined in a quiet environment using monosyllabic words. Late cortical waves were measured while subjects were engaged in an oddball task of 1 kHz frequent and 2 kHz rare tone stimuli. The latencies of event-related potential (N1, N2, P3) were compared for monaural, binaural, and bimodal hearing conditions.

Results

Significantly (p < 0.01, paired t-test) better speech perception for monosyllabic words was found for both binaural and bimodal hearing than monaural hearing. The latency of N1 did not significantly change for either binaural or bimodal hearing. On the other hand, the latency of N2 was significantly (p < 0.01, paired t-test) shorter for binaural and bimodal hearing than for monaural hearing. The latency of P3 was shorter for binaural and bimodal hearing than monaural hearing in all subjects, and the difference was statistically significant in both CI/CI and CI/HA groups (p < 0.01, paired t-test).

Conclusions

Better speech perception was obtained for binaural and bimodal hearing than for monaural hearing in CI subjects. The results obtained in the comparison of P3 latency agreed with that of speech perception. Thus, using bilateral hearing devices is recommended for CI subjects. We also found that event-related potentials were useful as an objective tool to assess the advantage of binaural and bimodal hearing for CI subjects.     

Advantages of binaural hearing provided through bimodal stimulation via a cochlear implant and a conventional hearing aid: A 6-month comparative study

Conclusions

Our study data demonstrate the additional benefit derived from continued use of a contralateral hearing aid (HA) post-cochlear implantation for speech recognition ability in quiet and in noise. Postoperative bimodal stimulation is recommended for all subjects who show some speech recognition ability in the contralateral ear as it may offer binaural listening advantages in various listening situations encountered in everyday life.

Objectives

To assess the benefits derived from bimodal stimulation for experienced HA users implanted with a cochlear implant (CI) (score?≥?20% in disyllabic test). The correlation between pre- and postoperative performance on speech perception measures was examined to determine additional criteria for recommending bimodal stimulation postoperatively.

Material and methods

A within-subject repeated-measures design was used, with each subject acting as their own control. Assessments were carried out preoperatively in aided monaural and best-aided conditions and at 6 months postoperatively in CI-alone, contralateral HA-alone and bimodal listening conditions. Speech recognition using Spanish words and sentences materials was assessed at conversational level and for soft speech in quiet. Speech comprehension in noise was assessed using word materials at a signal:noise ratio of +10, for coincident speech in noise and for spatially separated speech in noise. Twelve adult native Spanish subjects with a severe-to-profound hearing impairment who were experienced with optimally fitted conventional amplification and who displayed suboptimal speech understanding preoperatively were enrolled in the study. Preoperatively, conventional amplification was worn by five subjects binaurally and by seven monaurally.

Results

Postoperatively, superior speech recognition ability in quiet and in noise for disyllabic words was achieved using bimodal stimulation in comparison to performance for either monaural aided condition. Mean improvement in speech recognition in the bimodal condition was significant over performance in the CI-alone condition for disyllabic words in quiet at 70 (p=0.006) and 55 dB SPL (p=0.028), for disyllabic words in noise at +10 dB with speech and noise spatially separated with the noise source closest to the contralateral HA (S0NHA) (p=0.0005) and when the noise source was closest to the CI ear (S0NCI) (p=0.002). When testing word recognition in noise with speech and noise sources coincident in space, word scores were superior in the bimodal condition relative to the CI-alone condition but this improvement was not significant (p=0.07). The advantages of bimodal stimulation included significant effects of binaural summation in quiet and significant binaural squelch effects in both the S0NHA and S0NCI test conditions. All subjects showed superior performance in the binaural situation postoperatively relative to the best-aided condition preoperatively for one or more test situations.     

Contralateral hearing aid use in cochlear implanted patients: Multicenter study of bimodal benefit

Abstract Conclusion: The use of a hearing aid (HA) in combination with a cochlear implant (CI) significantly improved performance for speech perception in quiet, in noise, and for localization compared with monaural conditions. No significant differences in functional performance were observed following optimization of HA fitting. Objectives: To evaluate the binaural benefits derived from using a contralateral HA in conjunction with a CI in subjects with significant functional hearing in the nonimplanted ear and the effects of HA fitting optimization. Methods: Fifteen adult CI users, intra-subject controls, were enrolled in a prospective repeated-measure multicenter study. Evaluation of performance for speech understanding, localization, and subjective impressions was conducted before and following HA fitting optimization for CI alone, HA alone, and CI + HA. Results: For speech testing in quiet, bimodal scores were significantly better than for HA alone and CI alone conditions (p < 0.01). For speech and noise (S0N0) at 0° azimuth the scores were significantly better in the bimodal condition than for CI alone (p = 0.01), indicating binaural summation. When noise was presented to the HA side (S0NHA) bimodal scores were significantly better than for CI alone (p < 0.01 and p < 0.05, respectively), suggesting a significant binaural squelch effect. Sound localization ability was significantly improved in the bimodal condition compared with the CI alone condition (p = 0.002).     

Advantages of binaural hearing provided through bimodal stimulation via a cochlear implant and a conventional hearing aid: a 6-month comparative study

CONCLUSIONS: Our study data demonstrate the additional benefit derived from continued use of a contralateral hearing aid (HA) post-cochlear implantation for speech recognition ability in quiet and in noise. Postoperative bimodal stimulation is recommended for all subjects who show some speech recognition ability in the contralateral ear as it may offer binaural listening advantages in various listening situations encountered in everyday life. OBJECTIVES: To assess the benefits derived from bimodal stimulation for experienced HA users implanted with a cochlear implant (CI) (score=20% in disyllabic test). The correlation between pre- and postoperative performance on speech perception measures was examined to determine additional criteria for recommending bimodal stimulation postoperatively. MATERIAL AND METHODS: A within-subject repeated-measures design was used, with each subject acting as their own control. Assessments were carried out preoperatively in aided monaural and best-aided conditions and at 6 months postoperatively in CI-alone, contralateral HA-alone and bimodal listening conditions. Speech recognition using Spanish words and sentences materials was assessed at conversational level and for soft speech in quiet. Speech comprehension in noise was assessed using word materials at a signal:noise ratio of +10, for coincident speech in noise and for spatially separated speech in noise. Twelve adult native Spanish subjects with a severe-to-profound hearing impairment who were experienced with optimally fitted conventional amplification and who displayed suboptimal speech understanding preoperatively were enrolled in the study. Preoperatively, conventional amplification was worn by five subjects binaurally and by seven monaurally. RESULTS: Postoperatively, superior speech recognition ability in quiet and in noise for disyllabic words was achieved using bimodal stimulation in comparison to performance for either monaural aided condition. Mean improvement in speech recognition in the bimodal condition was significant over performance in the CI-alone condition for disyllabic words in quiet at 70 (p=0.006) and 55 dB SPL (p=0.028), for disyllabic words in noise at +10 dB with speech and noise spatially separated with the noise source closest to the contralateral HA (S0NHA) (p=0.0005) and when the noise source was closest to the CI ear (S0NCI) (p=0.002). When testing word recognition in noise with speech and noise sources coincident in space, word scores were superior in the bimodal condition relative to the CI-alone condition but this improvement was not significant (p=0.07). The advantages of bimodal stimulation included significant effects of binaural summation in quiet and significant binaural squelch effects in both the S0NHA and S0NCI test conditions. All subjects showed superior performance in the binaural situation postoperatively relative to the best-aided condition preoperatively for one or more test situations.     

Effect of extreme adaptive frequency compression in bimodal listeners on sound localization and speech perception

Objectives: This study aimed to improve access to high-frequency interaural level differences (ILD), by applying extreme frequency compression (FC) in the hearing aid (HA) of 13 bimodal listeners, using a cochlear implant (CI) and conventional HA in opposite ears.

Design: An experimental signal-adaptive frequency-lowering algorithm was tested, compressing frequencies above 160?Hz into the individual audible range of residual hearing, but only for consonants (adaptive FC), thus protecting vowel formants, with the aim to preserve speech perception. In a cross-over design with at least 5 weeks of acclimatization between sessions, bimodal performance with and without adaptive FC was compared for horizontal sound localization, speech understanding in quiet and in noise, and vowel, consonant and voice-pitch perception.

Results: On average, adaptive FC did not significantly affect any of the test results. Yet, two subjects who were fitted with a relatively weak frequency compression ratio, showed improved horizontal sound localization. After the study, four subjects preferred adaptive FC, four preferred standard frequency mapping, and four had no preference. Noteworthy, the subjects preferring adaptive FC were those with best performance on all tasks, both with and without adaptive FC.

Conclusion: On a group level, extreme adaptive FC did not change sound localization and speech understanding in bimodal listeners. Possible reasons are too strong compression ratios, insufficient residual hearing or that the adaptive switching, although preserving vowel perception, may have been ineffective to produce consistent ILD cues. Individual results suggested that two subjects were able to integrate the frequency-compressed HA input with that of the CI, and benefitted from enhanced binaural cues for horizontal sound localization.     

Abnormal Binaural Spectral Integration in Cochlear Implant Users

Bimodal stimulation, or stimulation of a cochlear implant (CI) together with a contralateral hearing aid (HA), can improve speech perception in noise However, this benefit is variable, and some individuals even experience interference with bimodal stimulation. One contributing factor to this variability may be differences in binaural spectral integration (BSI) due to abnormal auditory experience. CI programming introduces interaural pitch mismatches, in which the frequencies allocated to the electrodes (and contralateral HA) differ from the electrically stimulated cochlear frequencies. Previous studies have shown that some, but not all, CI users adapt pitch perception to reduce this mismatch. The purpose of this study was to determine whether broadened BSI may also reduce the perception of mismatch. Interaural pitch mismatches and dichotic pitch fusion ranges were measured in 21 bimodal CI users. Seventeen subjects with wide fusion ranges also conducted a task to pitch match various fused electrode–tone pairs. All subjects showed abnormally wide dichotic fusion frequency ranges of 1–4 octaves. The fusion range size was weakly correlated with the interaural pitch mismatch, suggesting a link between broad binaural pitch fusion and large interaural pitch mismatch. Dichotic pitch averaging was also observed, in which a new binaural pitch resulted from the fusion of the original monaural pitches, even when the pitches differed by as much as 3–4 octaves. These findings suggest that abnormal BSI, indicated by broadened fusion ranges and spectral averaging between ears, may account for speech perception interference and nonoptimal integration observed with bimodal compared with monaural hearing device use.     

Bilateral versus unilateral cochlear implants in children: Speech recognition,sound localization,and parental reports

Abstract

Objective: To compare bilateral and unilateral speech recognition in quiet and in multi-source noise, and horizontal sound localization of low and high frequency sounds in children with bilateral cochlear implants. Design: Bilateral performance was compared to performance of the implanted side with the best monaural speech recognition in quiet result. Parental reports were collected in a questionnaire. Results from the CI children were compared to binaural and monaural performance of normal-hearing peers. Study sample: Sixty-four children aged 5.1–11.9 years who were daily users of bilateral cochlear implants. Thirty normal-hearing children aged 4.8–9.0 years were recruited as controls. Results and Conclusions: Group data showed a statistically significant bilateral speech recognition and sound localization benefit, both behaviorally and in parental reports. The bilateral speech recognition benefit was smaller in quiet than in noise. The majority of subjects localized high and low frequency sounds significantly better than chance using bilateral implants, while localization accuracy was close to chance using unilateral implants. Binaural normal-hearing performance was better than bilateral performance in implanted children across tests, while bilaterally implanted children showed better localization than normal-hearing children under acute monaural conditions.     

Speech recognition materials and ceiling effects: considerations for cochlear implant programs

Cochlear implant recipients have demonstrated remarkable increases in speech perception since US FDA approval was granted in 1984. Improved performance is due to a number of factors including improved cochlear implant technology, evolving speech coding strategies, and individuals with increasingly more residual hearing receiving implants. Despite this evolution, the same recommendations for pre- and postimplant speech recognition testing have been in place for over 10 years in the United States. To determine whether new recommendations are warranted, speech perception performance was assessed for 156 adult, postlingually deafened implant recipients as well as 50 hearing aid users on monosyllabic word recognition (CNC) and sentence recognition in quiet (HINT and AzBio sentences) and in noise (BKB-SIN). Results demonstrated that for HINT sentences in quiet, 28% of the subjects tested achieved maximum performance of 100% correct and that scores did not agree well with monosyllables (CNC) or sentence recognition in noise (BKB-SIN). For a more difficult sentence recognition material (AzBio), only 0.7% of the subjects achieved 100% performance and scores were in much better agreement with monosyllables and sentence recognition in noise. These results suggest that more difficult materials are needed to assess speech perception performance of postimplant patients - and perhaps also for determining implant candidacy.     

Cochlear implantation in recipients with single-sided deafness: Audiological performance

Objective: To examine the auditory benefit of cochlear implants (CI) in patients with single-sided deafness (SSD).

Material and methods: Twenty patients with a normal pure tone audiogram (n?=?8) or moderate hearing loss (n?=?12) in one ear and a CI system MED-EL SONATA/CONCERTO?+?OPUS2 (n?=?12), COCHLEAR CI24RE(ST)?+?CP810 (n?=?7) and Advanced Bionics HiRes90?K?+?Harmony (n?=?1) in the contralateral ear and with at least 6 months of CI experience were tested with respect to directional hearing, speech perception in noise, binaural loudness matching, and binaural pitch matching. Twenty-six normal hearing controls were included for normative reference.

Results: Addition of the CI significantly improves directional hearing (percentage of correct source identifications improved from 14.9 to 15.6%, root mean square error decreased from 125 to 93°) and improves speech perception in noise (speech perception threshold median improved from ?2.3 to ?6.0?dB signal to noise ratio, equivalent to a binaural intelligibility level difference?=?3.7?dB). Alternate binaural loudness balancing showed that matching takes place at levels between 48 and 55?dB HL (group averages). In the pitch matching experiment, the standard deviation of the relative interaural frequency difference at 500, 1000, and 2000?Hz was 24.5, 22.8, and 24.0%, respectively (compared to 11.7, 14.4, and 12.3% in the control group).

Conclusions: In SSD, cochlear implantation considerably improves audiological performance in terms of directional hearing, binaural signal equivalence, and speech perception.     

助听器干预对西藏高原地区听障患者的疗效分析

目的 探讨助听器干预对久居(超过40年)西藏高原地区听障患者的疗效情况。方法 选取49例(63耳)助听器佩戴者进行分析，包括听力情况、听阈、助听器后言语及助听器效果国际问卷主观感受相关分析等，并对助听器补偿效果进行了综合评价。结果 63耳中，中度听力损失34耳，重度听力损失25耳，极重度听力损失4耳。其中单耳35例，问卷平均得分(20.34±4.39)分；双耳14例，问卷平均得分(27.07±4.16)分；双耳得分高于单耳分数。助听言语分辨率与问卷主观评估呈正相关(r=0.528,P<0.01)。助听阈值显示大多数患耳未得到最佳的听力补偿，但助听器干预前后听力比较具有统计学意义(P<0.05),高频听力补偿更为明显。助听后言语测听显示，助听后言语最大分辨率较助听前高(P<0.05)。结论 高原地区听障者对助听器的使用客观听力参数与主观评价相对一致，助听效果较为显著而且双耳验配较单耳验配更具优势，总体助听效果持肯定态度。     

Binaural interaction measured behaviorally and electrophysiologically in young and old adults

12 young men (mean age = 39.1 years) and 12 older men (mean age = 69.4 years) presenting some degree of sensorineural hearing loss were chosen so that the two groups were audiometrically matched. Behavioral tests of binaural interaction (BI) included binaural fusion, rapidly alternating speech perception, and masking level difference (at 500 Hz). There was a tendency toward better performance by the younger subjects for each of these tests, but these comparisons fell short of statistical significance. Auditory brainstem responses (ABRs) and middle-latency responses (MLRs) to clicks were recorded in both monaural and binaural modes, with off-line derivation of BI components. Latencies of wave V (in ABR) and waves Pa and Nb (in MLR) were prolonged in the older subjects for all conditions; this effect was independent of degree of hearing loss. BI components did not differ substantially between the two groups, except for a 0.45-ms latency difference for the 'N1' peak, as expected from the raw ABR data. MLRs for both groups showed a pattern of BI which was different from that seen in young subjects with normal hearing, in that latency for wave Pa in MLR was not reduced in the binaural condition. The young subjects showed the expected reduction of binaural wave Pa amplitude compared to monaural sum responses, while the older subjects, as a group, did not. No significant correlations were found between behavioral and electrophysiological tests.     

Long-term measurement of binaural intensity matches and pitch matches. I. Normal hearing

Changes in pitch perception and hearing thresholds over time have been observed in subjects with monaural fluctuating low-frequency hearing loss and Ménière's disease. Long-term suprathreshold audiometry and binaural pitch matches could provide information of these changes. Ten normal subjects were tested for stability of binaural intensity and pitch matches during 9–22 days in their homes with newly developed portable test equipment. Binaural pitch matches were measured using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear. The results showed stable binaural intensity matches (individual inter-quartile ranges, IQRs, 1.2 to 5.7 dB), but binaural pitch matches varied greatly (IQR ?0.6 to 5.3% at 0.25 kHz; IQR ?1.6 to 7.9% at 1 kHz). Binaural pitch-matching was much better in subjects who could define pitch precisely during monaural pitch matching. It was concluded that in future long-term evaluations of patients with fluctuating inner-ear function, binaural intensity matches could be suitable for all, but binaural pitch matching only for selected patients.     

Implementation and preliminary evaluation of ‘C-tone’: A novel algorithm to improve lexical tone recognition in Mandarin-speaking cochlear implant users

Objectives: Because of limited spectral resolution, Mandarin-speaking cochlear implant (CI) users have difficulty perceiving fundamental frequency (F0) cues that are important to lexical tone recognition. To improve Mandarin tone recognition in CI users, we implemented and evaluated a novel real-time algorithm (C-tone) to enhance the amplitude contour, which is strongly correlated with the F0 contour.

Methods: The C-tone algorithm was implemented in clinical processors and evaluated in eight users of the Nurotron NSP-60 CI system. Subjects were given 2 weeks of experience with C-tone. Recognition of Chinese tones, monosyllables, and disyllables in quiet was measured with and without the C-tone algorithm. Subjective quality ratings were also obtained for C-tone.

Results: After 2 weeks of experience with C-tone, there were small but significant improvements in recognition of lexical tones, monosyllables, and disyllables (P?Discussion: The real-time C-tone algorithm provided small but significant improvements for speech performance in quiet with no change in sound quality. Pre-processing algorithms to reduce noise and better real-time F0 extraction would improve the benefits of C-tone in complex listening environments.

Conclusions: Chinese CI users’ speech recognition in quiet can be significantly improved by modifying the amplitude contour to better resemble the F0 contour.     

Aging and the binaural advantage in reverberation and noise.

The consonant identification ability of younger normal-hearing adults and older adults with little or no peripheral hearing loss was assessed using monaural and binaural presentation in four listening conditions: quiet, noise, reverberation, and reverberation + noise. Performance was examined in terms of identification accuracy and amount of binaural advantage. Results suggest that the small amount of hearing loss in the older subjects limited their perception of distorted consonants. Neither age nor peripheral hearing loss was related strongly to the amount of benefit obtained from binaural presentation.     

VEMP recording by binaural simultaneous stimulation in subjects with vestibulo-cochlear disorders

To reduce the testing time of vestibular evoked myogenic potentials (VEMP) and the physical efforts of subjects, we studied if VEMP recording by binaural simultaneous stimulation in patients with vestibulo-cochlear disorders can be applicable as a screening test. Twenty-eight patients with vestibulo-cochlear disorders (12 men and 16 women, 22 to 77 years of age) were enrolled in this study. Patients were presented with binaural or monaural click (95 dBnHL) stimulation to record VEMPs. Their VEMP responses to binaural simultaneous stimulation were compared with those of monaural individual stimulation. Twenty-six of the 28 patients (93%) showed the same results in binaural simultaneous stimulation as in monaural individual stimulation. Amplitudes of p13-n23 to binaural simultaneous stimulation showed significant correlation to those of monaural individual stimulation ( r =0.774, P <0.0001 t -test). Peak latencies of p13 and n23 of binaural simultaneous stimulation also showed significant correlation to those of monaural individual stimulation (p13: r =0.684, P <0.0001 t -test, n23: r =0.657, P <0.0001 t -test). The binaural simultaneous stimulation method for VEMP recording is applicable for patients with vestibulo-cochlear disorders as a screening test in the clinic.     

Relationship between two measures of aided binaural advantage

The relationship between aided binaural squelch measured using a conventional paradigm and binaural squelch inferred from the ability to detect an intelligibility difference between binaural and pseudobinaural stimuli (presumably utilizing interaural time and intensity cues) was investigated. The conventional measures of aided binaural squelch included the NU-6 monosyllables and the high-predictability sentences from the revised SPIN test. For each measure, binaural squelch was derived by comparing the binaural intelligibility of speech-in-babble with corresponding monaural scores. Subjects were also asked to select the more intelligible hearing-aid-processed speech sample when presented with a paired-comparison task in which each pair consisted of a binaural and a pseudobinaural stimulus. Ability to choose the binaural stimulus as most intelligible was considered to be evidence of binaural squelch ability. Although the hearing-impaired subjects demonstrated typical binaural squelch for the conventional speech tests, they were usually unable to distinguish between the binaural/pseudobinaural pairs. These results suggest that (a) binaural squelch measured using conventional procedures does not necessarily quantify the listener's ability to profit from interaural differences, and (b) many hearing-impaired individuals may be unable to utilize interaural differences to enhance speech intelligibility in noise.     

Long-term measurement of binaural intensity matches and pitch matches. I. Normal hearing

Changes in pitch perception and hearing thresholds over time have been observed in subjects with monaural fluctuating low-frequency hearing loss and Ménière's disease. Long-term suprathreshold audiometry and binaural pitch matches could provide information of these changes. Ten normal subjects were tested for stability of binaural intensity and pitch matches during 9-22 days in their homes with newly developed portable test equipment. Binaural pitch matches were measured using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear. The results showed stable binaural intensity matches (individual inter-quartile ranges, IQRs, 1.2 to 5.7 dB), but binaural pitch matches varied greatly (IQR -0.6 to 5.3% at 0.25 kHz; IQR -1.6 to 7.9% at 1 kHz). Binaural pitch-matching was much better in subjects who could define pitch precisely during monaural pitch matching. It was concluded that in future long-term evaluations of patients with fluctuating inner-ear function, binaural intensity matches could be suitable for all, but binaural pitch matching only for selected patients.     

A systematic review of the impact of adjusting input dynamic range (IDR), electrical threshold (T) level and rate of stimulation on speech perception ability in cochlear implant users

Objective: To systematically review the evidence of how adjustments of the electrical threshold (T) level, input dynamic range (IDR) and electrical stimulation rate impact on speech perception for cochlear implant (CI) users.

Design: Systematic review.

Study sample: A search of two electronic data sources yielded 32 studies, which met the inclusion criteria. A quality assessment and two evidence-based practice (EBP) review rating schemes were used to grade studies.

Results: Due to the heterogeneity of speech perception measures, CI device type and study design, comparisons were made by structured review.

Conclusion: The quality of studies was found to be moderate to poor. Increasing T levels above behavioural threshold, or as a proportion of electrical dynamic range (EDR), has been demonstrated to improve perception of monosyllables in quiet and sentences in both quiet and in noise. Specific IIDR and IDR setting may improve perception of monosyllables in quiet and sentences in noise. However, no recommendation could be determined for setting rate of stimulation as speech perception varied significantly across rates examined. To optimise speech perception, a bespoke approach to parameter setting providing an individualised CI fitting is recommended; however, detail of how to optimise settings and the interactions between parameters is as yet unknown.     

Outcomes in adults implanted with the FLEXsoft electrode

Conclusion. Achieving deep insertions, as well as good speech perception results, the FLEX^soft electrode array allows for some preservation in subjects with measurable low frequency hearing, even after a period of time. This opens the door for future research in electrode design, hearing preservation research and drug delivery systems. Objectives. The FLEX^soft electrode is designed to be atraumatic to the structures of the cochlea during deep insertion of a cochlear implant electrode. This paper reports on the surgical and functional outcomes in implantations with the FLEX^soft electrode array. Patients and methods. Twenty-three adult subjects received a FLEX^soft electrode array and were assessed on speech perception tests (monosyllables, sentences in quiet and in noise), a subjective questionnaire (Nijmegen Cochlear Implant Questionnaire) and a pure-tone audiogram. Results at 1, 3, 6 and 12 months post first fitting were compared to scores from the preoperative interval. Results. Surgery was uneventful in all cases, the surgical handling was satisfactory and correct position of the electrode was achieved in all cases. Hearing could be preserved (as determined by the audiogram) in half of the subjects who had measurable audiograms preoperatively at the 1 month test interval, and in a quarter of subjects after 12 months of device use, despite deep insertion of the electrode. Speech perception scores showed significant improvement over time, as did quality of life scores, and were comparable to results with the standard electrode array as used in the COMBI 40+ and PULSARCI¹⁰⁰.